Upslope\LES Thread.....So the Mountain Folk and LEK's

[40/70 Benchmark]

Leave us synoptic dwellers be. lol

[powderfreak]

All joking aside, I do like the idea of an Upslope Thread... should've been started a while ago. I'll try to add some meaningful information when I get home this afternoon.

[adk]

Can this include lake enhanced or affected snowfall? It's not quite upslope as the green mountain crowd knows it - but on a prevailing W/SW flow of fhe the great lakes the ADK and even the Spine gets a pretty good does of snow enhanced by orographic uplift.

Anywho...it certainly looks juicy on the Euro towards the end of next week. Large maritime low spinning back westward into Maine/Can. Decent RH values. Looks like a good set-up for the Greens for sure.

[40/70 Benchmark]

Can this include lake enhanced or affected snowfall? It's not quite upslope as the green mountain crowd knows it - but on a prevailing W/SW flow of fhe the great lakes the ADK and even the Spine gets a pretty good does of snow enhanced by orographic uplift.

Anywho...it certainly looks juicy on the Euro towards the end of next week. Large maritime low spinning back westward into Maine/Can. Decent RH values. Looks like a good set-up for the Greens for sure.

Either that, or start a new thread for that.....I'll include it in the title just in case.

Grouping them together may work out because the population that each of them effects is relatively sparse.

[Ginx snewx]

Either that, or start a new thread for that.....I'll include it in the title just in case.

Grouping them together may work out because the population that each of them effects is relatively sparse.

http://www.americanwx.com/bb/index.php?/topic/1703-five-mile-radius-of-wilminton-mass/

[40/70 Benchmark]

http://www.americanw...wilminton-mass/

All sarcasm aside, this thread honestly serves a purpose as some of those guys seemed receptive to the idea.

[Wx4cast]

For now 2 "papers" on Upslope snow:

Upslope snow NY, VT, NH

Upslope Snow Research from BTV-NWSFO

[Ginx snewx]

For now 2 "papers" on Upslope snow:

Upslope snow NY, VT, NH

Upslope Snow Research from BTV-NWSFO

Nice fix your link on ENS you posted this morning

Days of upslope snow while the CP is partly cloudy with an afternoon snsh, great Powder at Sugarbush, love it.

[CoastalWx]

How about the ne mass subsidence zone thread???

[J.Spin]

Cool, it will be fun to see how this thread works. Perhaps a chance to test it out will be upcoming:

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BURLINGTON VT

LONG TERM /THURSDAY NIGHT THROUGH MONDAY... AS OF 415 AM EST TUESDAY...

A CUT OFF LOW IS PROGGED TO DEVELOP BY SATURDAY MORNING. THIS NEW LOW WILL JOIN WITH HIGH PRESSURE OVER THE ATLANTIC AND ANOTHER LOW EAST OF GREENLAND TO FORM AN OMEGA BLOCK...WHICH MEANS THE LOW WILL BECOME NEARLY STATIONARY THROUGH THE BEGINNING OF NEXT WEEK. THE RESULT WILL BE COOL CLOUDY WEATHER FOR THE NORTH COUNTRY WITH SCATTERED SNOW SHOWERS ...ESPECIALLY OVER THE NORTHERN MOUNTAINS.

[adk]

Cool, it will be fun to see how this thread works. Perhaps a chance to test it out will be upcoming:

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BURLINGTON VT

LONG TERM /THURSDAY NIGHT THROUGH MONDAY... AS OF 415 AM EST TUESDAY...

A CUT OFF LOW IS PROGGED TO DEVELOP BY SATURDAY MORNING. THIS NEW LOW WILL JOIN WITH HIGH PRESSURE OVER THE ATLANTIC AND ANOTHER LOW EAST OF GREENLAND TO FORM AN OMEGA BLOCK...WHICH MEANS THE LOW WILL BECOME NEARLY STATIONARY THROUGH THE BEGINNING OF NEXT WEEK. THE RESULT WILL BE COOL CLOUDY WEATHER FOR THE NORTH COUNTRY WITH SCATTERED SNOW SHOWERS ...ESPECIALLY OVER THE NORTHERN MOUNTAINS.

It's certainly a favorable set up for the greens. Certainly not the best for the ADK IMO.

[LakeEffectKing]

LOL! Synoptically you guys look great!

[powderfreak]

It's certainly a favorable set up for the greens. Certainly not the best for the ADK IMO.

It definitely has my attention... I like the idea of the cut-off and stalled low/mid/upper level features over the Northeast and Maritime region. I will have to see what papers wx4cast posted but here are some things I will be looking for over the next few days:

1) H85 wind flow... best for the northern Greens is pure NW. If you look at a topo map, the northern Green spine from I-89 northward actually curls northeast... NW flow hits perpendicular and maximizes lift. With that said, any variety of north to westerly flow will work, but due NW is best. You also want to see H85 winds of greater than 25kts for best production.

2) Solid RH from the SFC to H85. Good moisture at H7 is a plus, but not necessary as the lift occurs below that level. I've seen major upslope events with very dry air at H7... March 4, 2006 (I think that was a big one... 36" at Mansfield, even 14" at BTV) had Mount Washington at 6,200ft in bright, blue skies with solid overcast and a blizzard raging just below that level. Bretton Woods in NH picked up like two feet while the summit of MWN was in the sun. However, with moisture available aloft and a mid/upper level low overhead, we can actually get some good seeder-feeder type situations going which just enhances the snowfall rates.

3) H85 temps in the -10C to -18C range... dendrite snow growth is maximized as the best low level ascent is always maximized in that general H85 region. In general I've found if the H85 temp is -10C or lower, ratios will be very good.

4) I always thought that CAA at H85 is the best for upslope, but with CAA often comes drier air (naturally)...however low level lapse rates are often a lot higher and the atmosphere more unstable with CAA aloft. With that said I have seen some very large events take place with a WAA pattern at H85. This could happen with this upcoming period as warmer, maritime air gets wrapped back into our area. This is what caused the March 4, 2006 event. That event had WAA at H85 on a moist cyclonic flow from the Maritimes... with temperatures at H85 warming from like -18C to -10C. It maximized snow growth, and the warmer air coming in held more moisture, and it led to a massive event. Overall... pay attention to the temperature changes at H85 throughout the duration, as well as the low level lapse rates.

[kulaginman]

Great idea for a thread! I have a trip coming up to Jay Peak two weeks from Friday, so you guys need to start laying down a good base up there!! We've gone to Jay the weekend before Christmas every year since 2006, and I'm pretty sure last year was the first time we couldn't venture into the glades. Very disappointing since we basically go to Jay with the intent of spending the least amount of time possible on the groomers haha.

Anyway, I've been eyeing the potential from this weekend through a good portion of next week for some time now. Retrograding storm in southeast Canada FTW?

P.S. Excellent post by powderfreak!

[adk]

It definitely has my attention... I like the idea of the cut-off and stalled low/mid/upper level features over the Northeast and Maritime region. I will have to see what papers wx4cast posted but here are some things I will be looking for over the next few days:

1) H85 wind flow... best for the northern Greens is pure NW. If you look at a topo map, the northern Green spine from I-89 northward actually curls northeast... NW flow hits perpendicular and maximizes lift. With that said, any variety of north to westerly flow will work, but due NW is best. You also want to see H85 winds of greater than 25kts for best production.

2) Solid RH from the SFC to H85. Good moisture at H7 is a plus, but not necessary as the lift occurs below that level. I've seen major upslope events with very dry air at H7... March 4, 2006 (I think that was a big one... 36" at Mansfield, even 14" at BTV) had Mount Washington at 6,200ft in bright, blue skies with solid overcast and a blizzard raging just below that level. Bretton Woods in NH picked up like two feet while the summit of MWN was in the sun. However, with moisture available aloft and a mid/upper level low overhead, we can actually get some good seeder-feeder type situations going which just enhances the snowfall rates.

3) H85 temps in the -10C to -18C range... dendrite snow growth is maximized as the best low level ascent is always maximized in that general H85 region. In general I've found if the H85 temp is -10C or lower, ratios will be very good.

4) I always thought that CAA at H85 is the best for upslope, but with CAA often comes drier air (naturally)...however low level lapse rates are often a lot higher and the atmosphere more unstable with CAA aloft. With that said I have seen some very large events take place with a WAA pattern at H85. This could happen with this upcoming period as warmer, maritime air gets wrapped back into our area. This is what caused the March 4, 2006 event. That event had WAA at H85 on a moist cyclonic flow from the Maritimes... with temperatures at H85 warming from like -18C to -10C. It maximized snow growth, and the warmer air coming in held more moisture, and it led to a massive event. Overall... pay attention to the temperature changes at H85 throughout the duration, as well as the low level lapse rates.

The papers posted all generally state your same points. It's the RH from surface to summit, the wind speed and direction (10-25knt range) and the temperatures of the air column.

Do you ever take note of the lapse rates? Omega values forecasted? I spend a lot of time looking at UVV in the wasatch but oddly not in the Northeast. IDK.

Personally I find duration essential. The Green machine seems to perform best (I.E most efficiently) when it stays cranking for a sustained period. 8+ hours.

Also- as for the ADK- I'd say it's really impossible to measure the snowfall from these upslope events because the only reporting stations are Whiteface (which gets way less snow than the high peaks) and Mt. Van Hoovenburg which sits at only 2000ft. Many times I've seen 8 at MVH, 6 at WF and 12+ around 3k in the High peaks.

Speaking for RH values- why do you guys use for the Greens? Do you use the BTV sounding/model data?

[BxEngine]

Also- as for the ADK- I'd say it's really impossible to measure the snowfall from these upslope events because the only reporting stations are Whiteface (which gets way less snow than the high peaks) and Mt. Van Hoovenburg which sits at only 2000ft. Many times I've seen 8 at MVH, 6 at WF and 12+ around 3k in the High peaks.

Speaking for RH values- why do you guys use for the Greens? Do you use the BTV sounding/model data?

Is there really that much difference? Why doesnt Whiteface do as well?

[adk]

Is there really that much difference? Why doesnt Whiteface do as well?

Well sometimes its as simple as the ski area is on the south side of the mountain and all the snow is shielded and collected by the Norhwest and Northeast hills.

In more westerly events it sometimes gets showded by the High Peaks.

[Wx4cast]

Nice fix your link on ENS you posted this morning

Days of upslope snow while the CP is partly cloudy with an afternoon snsh, great Powder at Sugarbush, love it.

I don't know how the heck that happened.

[BxEngine]

Well sometimes its as simple as the ski area is on the south side of the mountain and all the snow is shielded and collected by the Norhwest and Northeast hills.

In more westerly events it sometimes gets showded by the High Peaks.

ahhh..makes sense...thanks. Been spending a lot more time up in the Dacks the last few years..trying to learn about it as much as I can.

[Wx4cast]

The papers posted all generally state your same points. It's the RH from surface to summit, the wind speed and direction (10-25knt range) and the temperatures of the air column.

Do you ever take note of the lapse rates? Omega values forecasted? I spend a lot of time looking at UVV in the wasatch but oddly not in the Northeast. IDK.

Personally I find duration essential. The Green machine seems to perform best (I.E most efficiently) when it stays cranking for a sustained period. 8+ hours.

Also- as for the ADK- I'd say it's really impossible to measure the snowfall from these upslope events because the only reporting stations are Whiteface (which gets way less snow than the high peaks) and Mt. Van Hoovenburg which sits at only 2000ft. Many times I've seen 8 at MVH, 6 at WF and 12+ around 3k in the High peaks.

Speaking for RH values- why do you guys use for the Greens? Do you use the BTV sounding/model data?

UVM and LLR instability are key too as they can both enhance the snowfall. Shear or lack thereof is key, too especially in the 1000 thru 700 millibar layer. SOmetimes too we look at the change of the LI (windex type event). Big changes in a 12 hour period (going down) can help in forecasting upslope snowfall eand amounts.

[powderfreak]

The papers posted all generally state your same points. It's the RH from surface to summit, the wind speed and direction (10-25knt range) and the temperatures of the air column.

Do you ever take note of the lapse rates? Omega values forecasted? I spend a lot of time looking at UVV in the wasatch but oddly not in the Northeast. IDK.

Personally I find duration essential. The Green machine seems to perform best (I.E most efficiently) when it stays cranking for a sustained period. 8+ hours.

Also- as for the ADK- I'd say it's really impossible to measure the snowfall from these upslope events because the only reporting stations are Whiteface (which gets way less snow than the high peaks) and Mt. Van Hoovenburg which sits at only 2000ft. Many times I've seen 8 at MVH, 6 at WF and 12+ around 3k in the High peaks.

Speaking for RH values- why do you guys use for the Greens? Do you use the BTV sounding/model data?

I must say I've never taken too much note of the lapse rates or omega values... I really should and think now I will start to this winter. I guess I like to see -20 UVV on a BTV sounding in the lower levels. And speaking of what soundings to use... BTV is usually best as it is just upstream of the upslope region. UVVs at BTV don't usually mean *all* that much as there can be subsidence at BTV and lift 15 miles east along the spine. However, during the solid events, something usually shows up on the BTV soundings.

The GFS and EURO have been keying in on this December 6-9th period as a possible long duration upslope snow event... now it won't snow the entire time (though could come close with flurries flying between periods of heavier snow shower activity) but we would be able to add up some decent totals over a 72 hour period.

Below is the omega from coolwx.com on the 12z GFS for BTV. Notice the increase past the 6th/00z of low level lift below 800mb. That tells me there is some sort of orographic response going on that has probably backed its way from the Spine into the BTV/CPV region.

I really like the coolwx.com site for a quick, easy glance at this sort of stuff. Here's a link to the 12z GFS relative humidity at BTV:

http://coolwx.com/cg...rent&field=relh

And here's what I like to see on the BTV soundings regarding RH... a good bit of low level moisture throughout the period, but notice the increase from the 6th/00z onward... that coupled with the blip of omega values shown above in the lower levels around the 6th/7th should produce at least some light snow in the Champlain Valley.

However, I bet downstream of the CPV this low level moisture would result in at least some accumulating snowfall when you couple that with the NW flow on the model. This is why the model is spitting out .01-.1" QPF consistently for 3 days (with occasionally higher .1-.25" amounts thrown in). And an important thing to remember is the GFS will always under-estimate the amount of QPF over the Greens in these situations (as will all of the global models... just like they do with lake effect), whereas the local BTV and BUF WRF/NAM models will be much closer to reality. What I look for with the global models is more "the signal" of them spitting out at least 0.01"+ QPF.

Overall it can be challenging to get the right information based on BTV being in the middle of the valley, but after a while you definitely get a sense/feel for what signals promote upslope and what don't.

A great source once an event draws near is the BTV 4km WRF model... this really helps me out as you'll see omega values spike over the Spine and its QPF forecasts are often pretty darn good. Take the snow shower/squall event on Saturday... it had .1-.25" in the Mansfield region for that minor event and the Mansfield cooperative observation came in with 0.19" during the period.

When this thing starts flagging 1"+ QPF along the spine for a 24-36 hour total, you can be sure a decent event is about to take place.

http://www.erh.noaa....tv/html/4kmwrf/

[Mad River]

Great idea for a thread! I have a trip coming up to Jay Peak two weeks from Friday, so you guys need to start laying down a good base up there!! We've gone to Jay the weekend before Christmas every year since 2006, and I'm pretty sure last year was the first time we couldn't venture into the glades. Very disappointing since we basically go to Jay with the intent of spending the least amount of time possible on the groomers haha.

Anyway, I've been eyeing the potential from this weekend through a good portion of next week for some time now. Retrograding storm in southeast Canada FTW?

P.S. Excellent post by powderfreak!

Jay should do really well with this set-up. While Stowe and Bolton Valley are pretty good at shaking out the snowglobe, Jay rises way above. There's nothing quite like driving up there when most of the way you see some scattered flurries in the air but once you get up the hill you see nothing but heavy snow. Enjoy your trip!!

[Mad River]

Thanks for the great posts Powder Freak!

[adk]

I must say I've never taken too much note of the lapse rates or omega values... I really should and think now I will start to this winter. I guess I like to see -20 UVV on a BTV sounding in the lower levels. And speaking of what soundings to use... BTV is usually best as it is just upstream of the upslope region. UVVs at BTV don't usually mean *all* that much as there can be subsidence at BTV and lift 15 miles east along the spine. However, during the solid events, something usually shows up on the BTV soundings.

The GFS and EURO have been keying in on this December 6-9th period as a possible long duration upslope snow event... now it won't snow the entire time (though could come close with flurries flying between periods of heavier snow shower activity) but we would be able to add up some decent totals over a 72 hour period.

Below is the omega from coolwx.com on the 12z GFS for BTV. Notice the increase past the 6th/00z of low level lift below 800mb. That tells me there is some sort of orographic response going on that has probably backed its way from the Spine into the BTV/CPV region.

I really like the coolwx.com site for a quick, easy glance at this sort of stuff. Here's a link to the 12z GFS relative humidity at BTV:

http://coolwx.com/cg...rent&field=relh

And here's what I like to see on the BTV soundings regarding RH... a good bit of low level moisture throughout the period, but notice the increase from the 6th/00z onward... that coupled with the blip of omega values shown above in the lower levels around the 6th/7th should produce at least some light snow in the Champlain Valley.

However, I bet downstream of the CPV this low level moisture would result in at least some accumulating snowfall when you couple that with the NW flow on the model. This is why the model is spitting out .01-.1" QPF consistently for 3 days (with occasionally higher .1-.25" amounts thrown in). And an important thing to remember is the GFS will always under-estimate the amount of QPF over the Greens in these situations (as will all of the global models... just like they do with lake effect), whereas the local BTV and BUF WRF/NAM models will be much closer to reality. What I look for with the global models is more "the signal" of them spitting out at least 0.01"+ QPF.

Overall it can be challenging to get the right information based on BTV being in the middle of the valley, but after a while you definitely get a sense/feel for what signals promote upslope and what don't.

A great source once an event draws near is the BTV 4km WRF model... this really helps me out as you'll see omega values spike over the Spine and its QPF forecasts are often pretty darn good. Take the snow shower/squall event on Saturday... it had .1-.25" in the Mansfield region for that minor event and the Mansfield cooperative observation came in with 0.19" during the period.

When this thing starts flagging 1"+ QPF along the spine for a 24-36 hour total, you can be sure a decent event is about to take place.

http://www.erh.noaa....tv/html/4kmwrf/

I use the same data. Just wanted to make sure I wasn't missing anything. I also think the High Res models do a decent job catching the up to the precip along the spine of the greens. Not just WRF run by BTV but also the two 48 hr models run by NCEP. As for the 'dacks SLK is a pretty good however I find the model QPF not really matching up. I think its because the jumbled nature of the high peaks and whiteface's location. Models just do a terrible job understanding the forcing and temps in that compact region. Its hard to get totals right in the area and I always subtract a touch for WF and add a degree ore two to the lower level temps (WF base sits almost 700 feet lower than KSLK) and subtract a degree or two from the h85 temps for WF. That summit is just COLD. For the rest of the high peaks I blend the totals from the models close my eyes and just write down a number.

Speaking of....I'm also pretty interested in the thursday - friday time period. With a little flow off the lake Ontario and the low pulling off towards the east and wrapping around a bit of moisture and 850 tmps in the -6 range I'd suspect some decent accumulating snows across the 'dacks and greens. Looks like maybe 3-5.

[CT Rain]

Jay is going to get crushed early next week. It's going to fun to watch the flakes fly.

[ono]

Jay is going to get crushed early next week. It's going to fun to watch the flakes fly.

time will tell...

[H2Otown_WX]

http://forecast.weather.gov/MapClick.php?lat=43.98688630934305&lon=-75.61958312988281&site=buf&smap=1&unit=0&lg=en&FcstType=text

[powderfreak]

Had some light snow with no accums down in the village at 5am, but we have a half inch to an inch above 1,500ft here this morning and upslope snow showers continue. Big fat wind-blown flakes.

Its not much but the ground is white again and its a start to what could be a pretty snowy 7 day period here in the upslope regions.

Awesome Winnoski Valley convergence going on along I-89 right now between the high terrain along the Spine.

Forecast looks great... chance of snow showers every day throughout the period. Look for POPs to come up as each day gets closer. Snow showers likely Saturday now and all model runs last night looked pretty darn good for a long-duration light snow event for the Greens.

[b]Friday: [/b]A chance of snow showers. Cloudy, with a high near 26. North wind between 7 and 9 mph. Chance of precipitation is 30%. New snow accumulation of less than a half inch possible. 

[b]Friday Night: [/b]A chance of snow showers. Cloudy, with a low around 21. North wind between 10 and 14 mph. Chance of precipitation is 50%.

[b]Saturday: [/b]Snow showers likely. Cloudy, with a high near 26. North wind between 13 and 15 mph. Chance of precipitation is 60%.

[b]Saturday Night: [/b]A chance of snow showers. Cloudy, with a low around 16. Chance of precipitation is 50%.

[b]Sunday: [/b]A chance of snow showers. Cloudy, with a high near 25. Chance of precipitation is 40%.

[b]Sunday Night: [/b]A chance of snow showers. Cloudy, with a low around 15. Chance of precipitation is 30%.

[b]Monday: [/b]A chance of snow showers. Cloudy, with a high near 23. Chance of precipitation is 40%.

[b]Monday Night: [/b]A chance of snow showers. Cloudy, with a low around 15. Chance of precipitation is 30%.

[b]Tuesday: [/b]A chance of snow showers. Cloudy, with a high near 23. Chance of precipitation is 40%.

[b]Tuesday Night: [/b]A chance of snow showers. Cloudy, with a low around 11. Chance of precipitation is 30%.

[b]Wednesday: [/b]A chance of snow showers. Cloudy, with a high near 20. Chance of precipitation is 30%.

[adk]

I'd say pops should be in the 80% range. Everything about the next 7 days says sustained mountain snow showers. I love the look for the upper Greens.

[ono]

I'd say pops should be in the 80% range. Everything about the next 7 days says sustained mountain snow showers. I love the look for the upper Greens.

it does look nice. i'm wondering about ratios

powderfreak- what's your formula for upslope snow ratios as far as lift, height, etc? it looks like it's not going to be ultra light snow, but not all that heavy either. 12:1 or a bit higher? if mother nature would oblige us, we could use a bit thicker snow ratio as it stands right now, anyway.

the GFS has BTV getting .86" QPF over the next 7 days. with orographic enhancement... gotta hold back here.